Although photographers undoubtedly terrified Witherspoon when they "besieged" her in April, there wasn't evidence of false imprisonment or other crimes, said William C. Hodgman, head of the district attorney's Target Crimes Unit.

"In this specific instance, we couldn't prove any criminal behavior by the paparazzi," Hodgman said Tuesday.

Local authorities are investigating whether increasingly aggressive celebrity photographers are initiating confrontations to capture lucrative photos. Prosecutors soon will decide whether to charge a photographer with assault with a deadly weapon for ramming his minivan into actress Lindsay Lohan's Mercedes-Benz sports car on May 31.

Witherspoon, the star of movies including "Legally Blonde" and "Sweet Home Alabama," told police that photographers swarmed her car when she left the Brentwood gym, tried to force her off the road and surrounded her when she reached the gated community in West Los Angeles where she lives with her husband, actor Ryan Phillippe (search), and two children.

Photographers told police they approached Witherspoon outside the gym only to tell her that one of their colleagues had scraped her vehicle.

Police examined videotape of the incident in the gym parking lot and at the community gates but couldn't determine that photographers detained Witherspoon.

"I have no doubt Ms. Witherspoon was besieged by the paparazzi that day," said Detective Jeff Dunn, head of the Los Angeles Police Department's Threat Management Unit. "But through witnesses and videotapes, we weren't able to corroborate the incident Ms. Witherspoon described."

Frank Griffin of the Bauer-Griffin celebrity photo agency acknowledged some photographers go too far. But the media, police and prosecutors often "blow out of proportion" allegations against paparazzi, he said.

"These prosecutors make a lot of noise so the politically active celebs keep supporting them," Griffin said, adding that his photographers were not involved in the Witherspoon incident.

In 1998, two photographers were convicted of false imprisonment for boxing in Gov. Arnold Schwarzenegger and his wife, Maria Shriver, outside their son's preschool. The incident took place before Schwarzenegger became governor.

Last weekend, a celebrity photographer found himself on the receiving end of an attack when he was shot in the leg with a round from a BB gun while staking out singer Britney Spears in Malibu. The Los Angeles County Sheriff's Department is investigating the incident.